Debt - Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Debt Disclosure [Abstract]
Interest paid on Senior Notes due 2024	$ 0	$ 3,378	$ 2,591	$ 10,134
Interest paid on Senior Notes due 2029	4,805	0	11,211	0
Interest paid on Revolving Credit Facility	508	767	1,438	2,520
Finance Lease, Interest Expense	1,833	927	3,441	2,852
Amortization of Debt Issuance Costs	415	372	1,306	1,143
Interest Expense, Other	51	45	225	261
Interest Costs Capitalized Adjustment	(4,375)	(393)	(6,972)	(921)
Interest Costs Incurred	$ 3,237	$ 5,096	$ 13,240	$ 15,989